Support arrangement for cam follower for actuating a gas exchange valve of an internal combustion engine

ABSTRACT

In a cam follower for actuating a gas exchange valve of an internal combustion engine, wherein the follower, at one end, rests on the gas exchange valve and, at the opposite end, rests on a housing structure of the internal combustion engine, at least two different operating modes are provided as the cam follower rests on the housing structure of the internal combustion engine via an adjustable support element and on the valve via an articulated element disposed in a seating bore formed into the cam follower.

This is a Continuation-In-Part Application of pending International Patent Application PCT/EP2005/012667 filed Dec. 26, 2005 and claiming the priority of German Patent Application 10 2004 060 433.9 filed Dec. 14, 2004.

BACKGROUND OF THE INVENTION

The invention relates to a cam follower for actuating a gas exchange valve of an internal combustion engine wherein one end of the follower rests on the gas exchange valve via an articulated element and the other end rests on an engine structure.

DE 198 50 404 A1 discloses a cam follower of generic type for actuating a gas exchange valve of an internal combustion engine. At a first end the cam follower rests via a contact face of an articulated element on a valve stem end face of the gas exchange valve and at a second end rests on a housing of the internal combustion engine. The cam follower is a sheet metal lever, wherein the articulated element can be integrated into the cam follower only by way of complicated connecting elements. The gas exchange valve cannot be operated in different operating modes, such as zero lift, for example.

It is the principal object of the present invention to provide a cam follower for operating a gas exchange valve of an internal combustion engine which is capable of acting on the gas exchange valve in at least two different operating modes, while, at the same time, the deviation between the center of the valve stem end face and the center of the cam follower contact face is reduced and the manufacture of the cam follower is simplified.

SUMMARY OF THE INVENTION

In a cam follower for actuating a gas exchange valve of an internal combustion engine, wherein the follower, at one end, rests on the gas exchange valve and, at the opposite end, rests on a housing structure of the internal combustion engine, at least two different operating modes are provided as the cam follower rests on the housing structure of the internal combustion engine via an adjustable support element and on the valve via an articulated element disposed in a seating bore formed into the cam follower.

The integration of an articulated element into the cam follower in combination with the position of the articulated element advantageously allow a large displacement travel between the valve stem end face and the contact face of the cam follower, without making the operating area, in which the cam follower and the valve stem end come into contact, too small.

The cam follower is advantageously an integrally cast lever, into which an articulated element can simply be integrated without further connecting elements. An optimum system rigidity is thereby achieved. The body of a conventional hydraulic valve clearance adjusting element (series-production element), without the means for performing the adjusting function, can advantageously be used as adjusting element.

The invention will become more readily apparent from the following description of an exemplary embodiment of the invention on the basis of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cam follower for actuating a gas exchange valve of an internal combustion engine, which at a first end, rests via an articulated element on the gas exchange valve and, at a second end, rests on an adjustable support element,

FIG. 2 shows the cam follower according to FIG. 1, in a state wherein the support element is switched to a cut-off mode, in which the gas exchange valve remains closed,

FIG. 3 shows the cam follower according to FIG. 1, the support element being switched to normal operation, in which the gas exchange valve is opened.

DESCRIPTION OF A PARTICULAR EMBODIMENT

FIGS. 1 to 3 show a cam follower 1 for actuating a gas exchange valve 2 of an internal combustion engine. The cam follower 1 can be actuated by cams 3 of a camshaft 4 of the internal combustion engine, which is only partially represented here, and at a first end 5 rests via an articulated element 6 on the gas exchange valve 2 and at a second end 7 rests on a housing structure of the internal combustion engine. In this exemplary embodiment the cam follower 1 is a rocker arm, other types of levers also being feasible. For reasons of rigidity, the cam follower 1 is preferably an integrally cast component.

The gas exchange valve 2 has a valve disk 8 and a valve stem 9 with a valve stem end face 10, which can be acted upon by a contact face 11 of the cam follower 1.

In order to be able to act upon the gas exchange valve 2 in at least two different operating modes whilst reducing the deviation between the center of the valve stem end face 10 and the center of the cam follower contact face 11, according to the invention the cam follower 1 at its second end 7 rests via an adjustable support element 12 on the housing of the internal combustion engine by way of a support element.

The support element is a conventional, adjustable support element 12, the basic design and operating principle of which is sufficiently know to persons skilled in the art. Briefly, the adjustable support element 12 has an outer housing 13 and an inner element 14 which is displaceable in relation to the outer housing 13, so that in at least one displacement position the outer housing 13 and the inner element 14 can be coupled by way of coupling means that are not visible here. In this exemplary embodiment the cam follower 1 rests via the inner element 14 on the outer housing 13 and hence indirectly on the housing of the internal combustion engine, not visible here.

The adjustable support element 12 permits at least two operating modes, that is to say a normal operating mode on the one hand and a cut-off mode on the other. In the normal operating mode according to FIG. 3, the outer housing 13 and the inner element 14 of the support element 12 are coupled together and the actuation of the cam follower 1 by the cams 3 of the camshaft 4 is transmitted to the gas exchange valve 2, so that the gas exchange valve 2 provides for a valve lift (FIG. 3). In the cut-off mode according to FIG. 2, the outer housing 13 and the inner element 14 of the support element 12 are displaceable against one another and when the cam 3 of the camshaft 4 acts upon the cam follower 1, the inner element 14 moves into the outer housing 13, with the result that the gas exchange valve 2 does not open (FIG. 2). Further operating modes with partial and/or multiple lifts are also feasible, that is to say the gas exchange valve 2 is actuated with different lifts and/or valve timings in the various operating modes depending on the position of the inner element 14 in the outer housing 13.

As already mentioned, the cam follower 1 at its first end 5 rests on the gas exchange valve 2 via an articulated element 6. The articulated element 6 comprises an outer body 15 and an inner body 16, which is capable of swiveling relative to the outer body 15 and is connected to the outer body 15, the outer body 15 being arranged in a seating bore (not visible here) formed into the cam follower 1. The articulated element 6 is firmly connected to the cam follower 1, by screwing, pressing or bonding the outer body 15 of the articulated element 6 into the seating bore of the cam follower 1. The inner body 16 of the articulated element 6 has the contact face 11 for acting upon the valve stem end face 10 of the gas exchange valve 2, both the contact face 11 and the valve stem end face 10 being preferably essentially planar faces. Other geometries are also feasible however, such as a spherically convex face which interacts with a spherically recessed face.

The cam follower 1 is designed in such a way that the two faces 10 and 11 always bear at least partially against one another in any operating mode of the internal combustion engine, that is to say the contact face 11 of the cam follower 1 is arranged securely on the valve stem end face 10 of the gas exchange valve 2. 

1. A support arrangement for a cam follower (1) for actuating a gas exchange valve (2) of an internal combustion engine, which follower, at a first end (5), rests on the gas exchange valve (2) and, at a second end (7), rests on a housing structure of the internal combustion engine, the cam follower support arrangement at the second end including an adjustable support element (12) mounted to the internal combustion engine and, at the first end, an articulated element (6) having an outer body (15) arranged in a seating bore of the cam follower (1) and an inner body (16), which is capable of swiveling relative to the outer body (15) and is connected thereto.
 2. The support arrangement for a cam follower as claimed in claim 1, wherein the articulated element (6) is firmly connected to the cam follower (1).
 3. The support arrangement for a cam follower as claimed in claim 1, wherein the outer body (15) of the articulated element (6) is joined to the cam follower (1) by one of screwing, pressing or bonding.
 4. The support arrangement for a cam follower as claimed in claim 1, wherein the articulated element (6) has a contact face (11) for acting upon a valve stem end face (10) of the gas exchange valve (2).
 5. The support arrangement for a cam follower as claimed in claim 4, wherein the contact face (11) is formed on the inner body (16) of the articulated element (6).
 6. The support arrangement for a cam follower as claimed in claim 4, wherein the two faces (10 and 11) are essentially planar faces.
 7. The support arrangement for a cam follower as claimed in claim 4, wherein one face (10 or 11) is spherically convex and the other face (10 or 11) is spherically recessed.
 8. The support arrangement for a cam follower as claimed in claim 4, wherein the two faces (10 and 11) always bear at least partially against one another in any operating mode of the internal combustion engine.
 9. The support arrangement for a cam follower as claimed in claim 1, wherein the cam follower (1) is embodied as a lever.
 10. The support arrangement for a cam follower as claimed in claim 1, wherein the cam follower (1) is an integrally cast component. 